In the field of medicine, lately, instead of capturing and diagnosis of a still image with radiation using a conventional film/screen or photostimulable phosphor plate, there is an attempt to capture a dynamic image of an object using a semiconductor image sensor such as a FPD (flat panel detector), etc. and to apply this in diagnosis. Specifically, speed of responsiveness of reading and deleting of image data of the semiconductor image sensor is used to successively emit pulsed radiation from a radiation source at a timing of reading and deleting of the semiconductor image sensor to perform a plurality of capturing per second to capture an object dynamically. By sequentially displaying a series of the plurality of images obtained by the capturing, a doctor is able to recognize a series of movement of the capturing body part.
In dynamic capturing, since capturing is performed a plurality of times, if the same amount of radiation as still image capturing is emitted in each capturing, amount of radiation exposure of the object becomes a considerable amount. Therefore, for example, patent document 1 describes a technique of dynamic capturing to suppress a total of emitted radiation in dynamic capturing to an amount equal to or less than that of still image capturing.    Patent Document 1: Japanese Patent Application Laid-Open Publication No. 2005-312775